Accumulator and charging means therefor



May 5, 1964 H. ALLEN 3,131,721

ACCUMULATOR AND CHARGING MEANS THEREFOR Filed May 31, 1962 -2 Sheets-Sheet 2 1 f/ererz A//e/7 INVENTOR.

BY W MgW ATTO/P/VE VJ United States Patent Ofl 3,131,721 ACCUMULATOR AND CHARGING MEANS THEREFOR Herbert Allen, Houston, Tex., assignor to Cameron Iron Works, Inc., Houston, Tex., a corporation of Texas Filed May 31, 1962, Ser. No. 199,134 6 Claims. ((Il. 137568) This invention relates to improvements in accumulators useful in operating equipment requiring a surge of liquid at a high pressure. For example, liquid accumulators are frequently provided at the head of an oil or gas well for use in closing the rams of a blowout preventer against high well pressures.

In one such accumulator, liquid is pumped into a vessel through a port in its lower end, and the vessel is charged with a gas to pressurize the liquid to the extent required for operating the equipment in question. The port is connected to such equipment by means of a conduit hav- 1 ing a valve disposed therein, so that when the high pressure operating liquid is needed, the valve need merely be opened to permit it to be discharged from the vessel by means of the charge gas thereabove. There is a valve member in the vessel for closing the port to prevent the loss of charge gas from the vessel when the operating liquid drains therefrom faster than it can be replaced by the fill pumps. The valve member is moved to port clos ing position by means of a body which floats on the liquid for downward the liquid level. When liquid is again pumped into the vessel, the body moves upwardly with it to permit the valve member to open the port and thereby prepare the accumulator for subsequent use.

An object of this invention is to provide an accumulator of this general type having a simple means for indicating at least the approximate level of the liquid within the' vessel at any given time.

Another object is to provide such an accumulator in which the fill pumps are automatically stopped and started without appreciable loss of charge gas; and, more particularly, in which such pumps are turned ofi and on without the necessity of a pressure signal from the vessel.

A further object is to provide such an accumulator which is more positive and dependable in operation, particularly in seating the valve member to close the discharge port in the vessel.

Still another object is to provide such an accumulator having a body for seating the valve member which is not susceptible of malfunction upon waterlogging.

These and other objects are accomplished in accordance with the present invention by an accumulator which, in its preferred form, is similar to the type described in that it includes a body at least partly immersible in the operating liquid within a vessel for reciprocating therein responsive to the rise and fall of the liquid level. Also, and again as in the prior accumulator above described, this body moves a valve member to a position closing the port when the liquid drops to a certain level so that the gas charge does not escape from the vessel through said port.

However, as distinguished from this earlier type, there is a stem on the valve member of the accumulator of my invention which extends sealably and reciprocably through the upper end of the vessel. The body is slidably mounted on the stem and rests on the valve member so as to urge the valve member downwardly as the liquid level drops and permit it to move upwardly as the liquid level rises. Thus, rather than floating in the usual sense, the body is supported not only by its buoyancy, but also by the upward force onthe stern and valve member due to the pressure within the vessel. need not be lighter than the liquid and reciprocates more movement in response to the fall of The body therefore sponse to the rise and fall of 3,131,721 Patented May 5, 1964 ice The outward extension of the stem also permits direct measurements and operations which have heretofore had to be made indirectly. For example, the stern provides at least an approximate visual indication of the level of liquid Within the vessel at any given time. Also, stem is useful in directly engaging switch means on the exterior of the vessel for stopping and starting the fill pumps or for performing other desired operations in rethe level of the operating fluid.

In the drawings, wherein like reference characters are used throughout to designate like parts:

FIG. 1 is a vertical sectional view of a vessel of a preferred embodiment of an accumulator constructed in the present invention,

. v drops to a certain level and by broken lines in the uppermost position it occupies to cause the pumps to be shut off when the vessel is filled with liquid to a desired extent;

FIG. 2 is a side view, partly in section and upon an enlarged scale, of the outwardly extending end of the tion of FIG. 1; and

FIG. 3 is a vertical sectional view of the stem and housing, as seen along broken line 3-3 of FIG. 2, and showing switch means in solid lines in the position it occupies when moved by the stem to shut off the pumps and in broken lines in the position it occupies when moved by the stern, upon lowering of the liquid level, to start the pumps.

With reference now to the scribed drawings, the vessel 10 is shown in FIG. 1 to be substantially cylindrical and to comprise upper and lower parts 1 1 and 12 which are closed at one end and welded together at their opposite open ends. A fitting 13 secured by bolts 14 within an opening'15 in the lower end of the vessel 10 has a port 16 therein which connects the lower end of the vessel with a conduit 17. Operating liquid such as oil maybe pumped into the vessel through the conduit 17 and port 16 and then pressurized to a desired extent by means of a charge of gas such as nitrogen introduced into the vessel through a fitting 18. As previously described, the conduit 17 is conventionally connected to suitable manifolding (not shown) both for discharging the within the vessel to the equipment to be actuated and for introducing liquid into the accumulator, as mentioned above.

The port 16 is adapted to be closed by means of a valve member 21 seat'able upon a seat '22 about the upper end of the po A stem or rod'24 is connected to the valve member by means of a tubular extension 25 threaded at 26 to the lower end of the rod and welded at 26a to the upper side shown in FIGS. 2 and 3, the upper 'end of the rod 24 extends through an opening 10 for communication with details of the above-dethe ambient atmosphere.

in the upper end of the vessel The body 19 is also cylindrical for fitting closely but freely within the vessel as it reciprocates vertically therein. Since the body is normally partly immersed in the operating fluid, as will be described below, it reduces the gasliquid interface to a minimum, without at the same time interfering with free reciprocation of the body and the parts movable therewith. The inner wall of the body is formed of a tubing 20 slidably disposed about the tubular extension and extending downwardly to rest on the top side of the valve member 21. Thus, when the liquid within the vessel falls to the level LL, the body 19 will move downwardly to force the valve member 21 to the port closing position shown in the solid lines of FIG. 1.

However, when operating liquid is introduced into the vessel to force the valve member 21 upwardly from the seat 22, whereby liquid rises to a level such as shown in UL, the valve member will rise with the body and stem, as shown by the broken lines of FIG. 1, so as to open the port 16. Thus, as long as the body 19 is above the lowermost level shown in FlG. 1, the port 16 is maintained open, so that the operating fluid is free to be discharged from the vessel merely upon manipulation of a valve in the manifold connected with the conduit =17.

As shown in FIG. 1, the lower seating surface on the valve member 21 is tapered downwardly and inwardly similarly to the seat 22 about the port 16. The upper end of this seat is surrounded by a rubber ring 23 which not only seals between the vessel and the fitting 15, but also provides a resilient seal with an outer portion of the seating surface of valve member 21 in its port closing position.

The tubular extension is guidably reoiprocable over the upper end of a rod 27 connected to the fitting 13 and extending upwardly into the vessel through the port 16. The upper end of the extension 25 is also guided by means of a ring 28 supported by radially extending bars 29 which are, in turn, supported from an outer ring 30 fitted tightly within the vessel adjacent a shoulder 31 on upper vessel part 11 and disposed over the separation between upper and lower vessel parts.

The freely reciprocable rod 24 is surrounded by an inner seal ring 33 carried in a counterbore at the upper end of opening 32 and an outer seal ring 34 carried with a counterbored portion of a gland 35 which is held down against the seal ring 33 in a manner to be described below. The outer seal ring is in turn held down on the inner gland 35 by means of an outer gland 37 secured thereto, as by bolts 3711 (see FIG. 3).

As shown in FIG. 3, there is a port 38 extending laterally through the gland 35 to connect with the rod 24 intermediate the seal rings 3-3 and 34. As indicated in FIG. 1, the outer end of this port connects with a conduit 39 which extends downwardly to connection with a port 40 in the lower end of the vessel. A needle valve 41 or the like is disposed within the conduit 39 to admit operating liquid from the lower end of the vessel into the space between the two seal members. This not only reduces friction between the rod and seal members, but also provides a highly efiicient seal about the rod 24 because even if gas within the upper end of the vessel should leak past the inner ring 33, it will be sealed by the operating liquid between the two seal rings. Furthermore, a small amount of such liquid could be supplied to the space through the conduit 39 to replenish any which might leak past the outer seal ring 34.

As shown in FIGS. 2 and 3, a crosshead on the upper end of rod 24 is slidable over guide posts 47 mounted on the vessel. More particularly, and as shown in FIGS. 1 and 2, the posts have threaded lower ends 36 for connection within sockets on the upper end of such vessel and shoulders 36a for seating on the gland 35 to hold it down in the manner previously mentioned.

In operation, the body 19 is in equilibrium between a downward force due to its weight and upward forces due to (A) the weight of liquid displaced by'the body and (B) the piston effect on the rod '24 caused by gas pressure in the vessel. It is preferred, therefore, that the weight of the body he at least as great as the piston force on the rod at the highest pressure of gas in the vessel'that is, at the uppermost position of the bodyin order that the body remain at least partially immersed in the operating liquid. It is also preferred that the weight of the body be less than the weight of the liquid it displaces when fully immersed plus the piston force at the lowest pressure of gas in the vessel-that is, at the lowermost position of the body-in order that the body not sink before the desired lowermost level of the liquid is achieved. These limits permit a wide range of body weights including body weight greater than the weight of the displaced liquid when the body is completely immersed. This makes possible a construction in which the body may be filled with operating liquid through opening 19a and is, therefore, not affected by entry thereinto of such liquid. It also makes possible a valving which is more positive and less subject to wire drawing.

As best shown in FIGS. 2 and 3, a housing 42 is removably secured to the upper end of the vessel 19 about the glands '35 and 37. There is a vertically extending slot 43 in one side of the housing through which a rod 44 extends outwardly from the crosshead 45 on the upper end of the rod 24. More particularly, a knob 46 or other means is provided on the end of the rod for clearly indicating its vertical level with respect to the slot. Obviously, suitable indicia may be provided along the edge of the slot to permit the viewer to otbain at least an approximate indication of the level of liquid within the vessel.

The upper ends of the posts 47 are connected together by a plate 48 which is held down on the upper ends of such posts by means of nuts 49. As shown in FIG. 3, the side of crosshead 45 opposite the rod 44 is provided with a projection 50 for actuating switch means 51 which, as previously described, may be provided for automatically starting and stopping the pumps for filling vessel 10. In the illustrated embodiment of the invention, the switch means includes a Y-shaped arm 52 pivotally mounted on a pin 57 supported from brackets 58 depending from plate 48. Rollers 53 and 54 on the opposite ends of the Y of the arm 52 are engageable by the projection 50 during reciprocation of the rod 24 so as to swing the arm between the switch closing position shown in solid lines and the switch opening position shown in broken lines. Thus, as the vessel is being filled, the arm 52 will be disposed in the switch opening position so that the projection 50 is raised past the roller 54 and into engagement with the roller 53.

Continued upward movement of the projection on the stem will then raise the rollers 53 and thus swing the arm 52 in a clockwise direction so as to close the switch and thereby shut off the pumps. Then, when the liquid level in the vessel drops, as upon discharge of the liquid therefrom into the equipment to be actuated, the projection 50 will move downwardly with the stem 24 so as to engage the roller 54. Continued downward movement of such projection will move the roller 54 downwardly to its dotted line position so as to swing the arm 52 to switch opening position and permit the projection St) to be moved past the roller 54. This, of course, turns the pumps back on, at least until such time that the projection 50 has again been raised to the position shown in FIG. 3.

As shown diagrammatically in FIG. 3, the stem of the Y-shaped arm 52 is connected to a toggle switch 55 or the like disposed within a fluid-actuated line 56. As previously mentioned, the clockwise swinging of the arm to the solid line position will close the switch, while the swinging of the arm in a counterclockwise direction to its broken line position will open same. The switch may be mounted on the housing, as by means of a bracket 59 bolted to one side thereof.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed is:

1. An accumulator, comprising a vessel having a discharge port in its lower end, liquid in the vessel having a charge of gas contained thereabove so that the pressure thereof varies with the rise and fall of the liquid, a valve member for opening and closing the port, a stem extending sealably and reciprocably through the upper end of the vessel, and a body about the stem at least partly immersible in the liquid and vertically reciprocable within the vessel in response to the fall of the liquid level therein for moving the valve member from port-opening to port-closing position when said liquid drops to a certain level, the total gravitational force on said body and stem and all parts movable with the stem being greater than the buoyancy of said body and greater than the upward piston force on the stem at the uppermost position of the body when the gas pressure is at a maximum, butbeing less than the total of the weight of the liquid displaced by said body and the upward piston force on the stem at the lowermost position of the body when the gas pressure is at a minimum.

2. A11 accumulator of the character defined in claim 1, including means in the vessel for guiding said stem during reciprocation within the vessel.

3. An accumulator, comprising a vessel having a discharge port in its lower end, liquid in the vessel having a charge of gas contained thereabove so that the pressure thereof varies with the rise and fall of the liquid, a valve member for closing the port, a stem extending upwardly from the valve member and sealably through the upper end of the vessel, a hollow body about the stem and fitting closely within the vessel for vertical reciprocation therein responsive to the rise and fall of the liquid level, and means on the body for moving said valve memher to port-closing position when said liquid drops to a certain level, the total gravitational force on said body and stem and all parts movable with the stem being greater than the buoyancy of said body and greater than the upward piston force on the stem at the uppermost position of the body when the gas pressure is at a maximum, but less than the total of the weight of the liquid displaced by said body and the upward piston force on the stem at the lowermost position of the body when the gas pressure is at a minimum.

4. An accumulator of the character defined in claim 3, including means for at least partially filling said hollow body with liquid.

5. An accumulator, comprising a vessel adapted to contain liquid with a gas charge thereabove and having a discharge port in its lower end, means including a stem extending sealably through the upper end of the vessel and responsive to the liquid level within the vessel for closing said port when the liquid drops to a certain level to prevent the escape of charge gas from the vessel, switch means on the exterior of the vessel adapted to stop and start pump means for introducing liquid into the vessel, and means on the stem for moving said switch means between pump stopping and starting positions.

6. An accumulator, comprising a vessel adapted to contain liquid with a gas charge thereabove and having a discharge port in its lower end, means including a stem extending sealably through the upper end of the vessel and responsive to the liquid level within the vessel for closing said port when the liquid drops to a certain level to prevent the escape of charge gas from the vessel, spaced-apart seal means about the stem, and means connecting the liquid in the vessel with the stem intermediate said seals.

References Cited in the file of this patent UNITED STATES PATENTS 343,437 Cramer June 8, 1886 1,245,525 Striefler Nov. 6, 1917 2,169,561 Layne Aug. 15, 1939 2,979,070 Payne Apr. 11, 1961 FOREIGN PATENTS 777 Great Britain Feb. 26, 1879 1,092,381 France Nov. 10, 1954 

1. AN ACCUMULATOR, COMPRISING A VESSEL HAVING A DISCHARGE PORT IN ITS LOWER END, LIQUID IN THE VESSEL HAVING A CHARGE OF GAS CONTAINED THEREABOVE SO THAT THE PRESSURE THEREOF VARIES WITH THE RISE AND FALL OF THE LIQUID, A VALVE MEMBER FOR OPENING AND CLOSING THE PORT, A STEM EXTENDING SEALABLY AND RECIPROCABLY THROUGH THE UPPER END OF THE VESSEL, AND A BODY ABOUT THE STEM AT LEAST PARTLY IMMERSIBLE IN THE LIQUID AND VERTICALLY RECIPROCABLE WITHIN THE VESSEL IN RESPONSE TO THE FALL OF THE LIQUID LEVEL THEREIN FOR MOVING THE VALVE MEMBER FROM PORT-OPENING TO PORT-CLOSING POSITION WHEN SAID LIQUID DROPS TO A CERTAIN LEVEL, THE TOTAL GRAVITATIONAL FORCE ON SAID BODY AND STEM AND ALL PARTS MOVABLE WITH THE STEM BEING GREATER THAN THE BUOYANCY OF SAID BODY AND GREATER THAN THE UPWARD PISTON FORCE ON THE STEM AT THE UPPERMOST POSITION OF THE BODY WHEN THE GAS PRESSURE IS AT A MAXIMUM, BUT BEING LESS THAN THE TOTAL OF THE WEIGHT OF THE LIQUID DISPLACED BY SAID BODY AND THE UPWARD PISTON FORCE ON THE STEM AT THE LOWERMOST POSITION OF THE BODY WHEN THE GAS PRESSURE IS AT A MINIMUM. 